Compact Dual-Band Textile PIFA for 433-MHz/2.4-GHz ISM Bands

A textile planar inverted-F antenna (PIFA) is proposed. By co-designing the PIFA antenna and the ground plane, a wide matching bandwidth is achieved around 433 MHz for a relatively small electrical size (0.202 × 0.115 × 0.01 λ
₀
³
). A slot within the PIFA patch enables the 2.4-GHz operating band. The measured bandwidths are 35 and 309 MHz in the lower and upper bands, respectively. The corresponding radiation efficiencies are 48% and 64%. The analysis of the effect of bending and the on-body characterization show the robust performance of the antenna.